RUI: The genetics and mathematical modeling of pollen performance

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Flowering plants are not reproductively indiscriminate. In other words, during reproduction, some pollen have greater mating success. Differences in pollen performance, often revealed during pollen competition, have long been recognized as evolutionarily significant and agriculturally important. While there is a rich history of work focused on the evolutionary pressures that lead to differential pollen performance, we lack a functional genetic understanding of the process. Here, the researchers will exploit the model plant Arabidopsis thaliana to define the genetic elements that direct pollen performance, and utilize new microscopy assays to quantify the process of pollen competition. Defining the genetics of pollen performance and modeling the process of pollen competition will transform our ability to intelligently modify crop varieties with resilient and selective pollination systems in the future. This work will be conducted by undergraduate students who will participate in an enhanced research experience through the establishment of on-site multiply-mentored scientific teams that employ an interdisciplinary approach. Student teams, duel mentored by a biologist and mathematician, will coordinate experimental planning, data collection and mathematical modeling to accomplish the research goals of this proposal, and also participate in K-12 outreach to schools in Chicago and Northwest Indiana. Thus, this project offers a large number of undergraduate and K-12 students, many from underrepresented groups in science, the opportunity to integrate mathematical thinking into questions of basic biology, and to do so in collaborative groups. Such work has great potential to expose and recruit students to research professions.The researchers have previously used recombinant inbred lines and genome-wide association mapping to identify the major loci that influence pollen performance in Arabidopsis thaliana. Additionally, they have developed a microscopy approach that allows the visualization and quantification of the behavior of individual pollen populations during competitions. This approach offers the opportunity to quantify how differential pollen performance during pollen competition directs nonrandom mating, as pollen tubes leave a visible trace of their movements, rates and behaviors as they compete to deliver sperm to eggs. In this project, the researchers will identify and characterize the genes responsible for differential pollen performance and how their natural variation influences the process of pollen competition. These data provides, for the first time, the tools needed to mathematically model the process of pollen competition. This work will provide a deeper mechanistic understanding of how pollen performance influences pollen competition, pollen interference, nonrandom mating and the process of fertilization. The evolutionary significance of this extends beyond plants; there are deep parallels between the well-studied process of sperm competition and pollen competition, yet there are not robust physical models for either. This study represents a unique opportunity to define the connections between variation in genes and behaviors that can direct nonrandom mating, a process of immense evolutionary significance in sexual organisms.